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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
   <script>
    //    let arr = [1, 2, 3, 4, 5];
    //     let arr1 = arr.map(item => item + 2);
    //     console.log(arr1);   //可以得到结果  [3,4,5,6,7]
    //     console.log(arr); 
let i=1
let b=i+2
console.log(b);
       
   </script> 
</body>
</html>